The present invention relates to a solid state imaging device including a light receiving portion having an opening portion formed thereon, such as a CCD solid state imaging device or the like.
In the solid state imaging device, the optical system thereof tends to become as small as ⅓ inch or xc2xc inch. In correspondence with the reduction in size and the increase in number of pixels in the solid state imaging devices, the opening of the light receiving portion is becoming smaller.
If the opening of the light receiving portion is expanded for the purpose of improving the sensitivity, the smear becomes apt to occur because of light incidence upon the charge transfer portion. Therefore, there is a limit in making the opening of the light receiving portion larger.
Furthermore, if it is attempted to improve the sensitivity by electrically amplifying the signal charge obtained by the photoelectric conversion of incident light on the light receiving portion, the influence of noise upon the signal value also becomes large and the signal-to-noise characteristic is deteriorated.
In the device fabrication, white points are caused by a crystal defect of the semiconductor substrate or contamination in the fabrication process and so on. As for the white points, minute white points which cannot be completely controlled even now and white points of a level which has not been regarded as defective until now exert a great influence. This results in a problem of reduction in yield.
In order to solve the above described problems, an object of the present invention is to provide a solid state imaging device which has been improved in signal-to-noise characteristics and sensitivity and which can be fabricated with high yield.
A solid state imaging device according to the present invention includes light receiving portions having opening portions formed as pixels, and low reflection films formed over the opening portions of the light receiving portions, wherein lights incident upon the light receiving portions have a plurality of colors selected for respective pixels, and the low reflection film has a film thickness or a refractive index selected for each pixel so as to correspond to a color of a light incident upon the light receiving portion.
Another solid state imaging device according to the present invention includes light receiving portions having opening portions formed as pixels, and low reflection films formed over the opening portions of the light receiving portions, and films disposed over the low reflection films to supply hydrogen.
In the above described configuration of the present invention, the proportion of the light incident upon the light receiving portion being reflected is reduced by providing the low reflection films on the light receiving portion. Thus, it is possible to reduce the proportion of light reflected and let off from the light receiving portion and increase the amount of received light. Therefore, the sensitivity of the solid state imaging device can be improved.
Furthermore, lights incident upon the light receiving portions have a plurality of colors selected for respective pixels, and the low reflection film has a film thickness or a refractive index selected for each pixel so as to correspond to a color of a light beam incident upon the light receiving portion. As a result, the sensitivity can be optimized for each color.
According to the above described another configuration, films for supplying hydrogen are disposed over the low reflection films. Thereby, it is possible to supply hydrogen to the surface of the substrate and lower the interface level.
In accordance with the present invention, a solid state imaging device includes light receiving portions having opening portions formed as pixels, and low reflection films formed over the opening portions of the light receiving portions, wherein lights incident upon the light receiving portions have a plurality of colors selected for respective pixels, and the low reflection film has a film thickness or a refractive index selected for each pixel so as to correspond to a color of a light beam incident upon the light receiving portion.
In accordance with the present invention, in the solid state imaging device described above, the film thickness of the low reflection films having same refractive index is changed pixel by pixel so as to correspond to the color of the light beam incident upon the light receiving portion.
In accordance with the present invention, in the solid state imaging device described above, the low reflection films are formed by a plurality of films having different refractive indexes, and the refractive index of the low reflection films is changed pixel by pixel so as to correspond to the color of the light beam incident upon the light receiving portion.
In accordance with the present invention, in the solid state imaging device described above, the film thickness and refractive index of the low reflection films are changed pixel by pixel so as to correspond to the color of the light beam incident upon the light receiving portion.
In accordance with the present invention, a solid state imaging device includes light receiving portions having opening portions formed as pixels, and low reflection films formed over the opening portions of the light receiving portions, and films disposed over the low reflection films to supply hydrogen.
In accordance with the present invention, in the above-mentioned solid state imaging device, the low reflection films are formed so as to be narrower in width than the opening portions of the light receiving portions.
In accordance with the present invention, the abovementioned solid state imaging device has such a configuration that in pixels of a central portion each of the low reflection films is formed in center of the opening portions of the light receiving portions, whereas in pixels of peripheral portions each of the low reflection films is formed so as to be displaced from the center of the opening portions of the light receiving portions to the outside.